Question

我正在使用INFORMIX数据库。

我已经在表中添加了forign键而没有给它起一个名字，例如。

ALTER TABLE myreport ADD CONSTRAINT FOREIGN KEY (rid) REFERENCES report(id), ADD CONSTRAINT FOREIGN KEY (uid) REFERENCES user(id);

我想根据select语句的输出删除其forign键约束，如下所示：

ALTER TABLE myreport DROP CONSTRAINT (
   SELECT b.constrname
       FROM
           systables a, sysconstraints b, sysindexes c, syscolumns d
       WHERE
           a.tabname = 'myreport' AND (d.colname='rid' or d.colname='uid')
       AND
           b.tabid = a.tabid
       AND
           c.idxname = b.idxname
       AND
           d.tabid = a.tabid
       AND
       (
           d.colno = c.part1 or d.colno = c.part2 or d.colno = c.part3 or d.colno = c.part4 or
           d.colno = c.part5 or d.colno = c.part6 or d.colno = c.part7 or d.colno = c.part8 or
           d.colno = c.part9 or d.colno = c.part10 or d.colno = c.part11 or d.colno = c.part12 or
           d.colno = c.part13 or d.colno = c.part14 or d.colno = c.part15 or d.colno = c.part16
       )
);

会抛出错误201: A syntax error has occurred.

但是当我单独运行它时它工作正常并提供如下输出：

：选择：

SELECT b.constrname
       FROM
           systables a, sysconstraints b, sysindexes c, syscolumns d
       WHERE
           a.tabname = 'myreport' AND (d.colname='rid' or d.colname='uid')
       AND
           b.tabid = a.tabid
       AND
           c.idxname = b.idxname
       AND
           d.tabid = a.tabid
       AND
       (
           d.colno = c.part1 or d.colno = c.part2 or d.colno = c.part3 or d.colno = c.part4 or
           d.colno = c.part5 or d.colno = c.part6 or d.colno = c.part7 or d.colno = c.part8 or
           d.colno = c.part9 or d.colno = c.part10 or d.colno = c.part11 or d.colno = c.part12 or
           d.colno = c.part13 or d.colno = c.part14 or d.colno = c.part15 or d.colno = c.part16
       )

给予：

constrname  r169_278
constrname  r169_279
constrname  r169_280

ALTER TABLE：

ALTER TABLE cuicscheduledreports DROP CONSTRAINT (r169_278, r169_279)

显示成功日志

所以我需要一组能够以动态方式实现我的需求的查询，因为它将用作不同系统上db的迁移

Answer 1

DROP CONSTRAINT不允许使用约束名称的子查询。必须明确命名约束名称。

此处记录了DROP CONSTRAINT的语法：https://www.ibm.com/support/knowledgecenter/SSGU8G_12.1.0/com.ibm.sqls.doc/ids_sqs_0069.htm

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只允许以逗号分隔的名称列表，而不是子查询。

您必须分两步完成此任务，如您所发现的那样。

将来，您应该避免编写虚构的语法并期望它能够正常工作。查看手册以了解语法选项。

根据informix中复杂select语句的输出删除外键约束？

1 个答案: